The common medical syringe has been used for many years to inject medications and other fluids into the bloodstream of patients. Syringes are also used to aspirate or withdraw fluids, such as blood samples, from patients. Such syringes typically comprise a cylindrical syringe barrel having a tubular needle mounted to one end and a plunger slidably disposed within the barrel for injecting and aspirating fluids.
Once inserted into a patient's bloodstream, a syringe needle can and often does become contaminated with microscopic viruses or bacteria that may be present in the bloodstream. Such a contaminated needle can be extremely dangerous to medical personnel handling the syringe since an accidental needle prick or even contact with the exposed needle can infect them with the virus or bacteria present on the needle. This danger is particularly acute in emergency medical situations in which there is often no time to dispose of contaminated needles carefully and properly.
Many cases of infection of medical personnel through accidental contact with contaminated syringe needles are documented each year. Sometimes, doctors and nurses who are accidentally pricked or contact a contaminated needle contract fatal diseases such as hepatitis and, more recently, Acquired Immune Deficiency Syndrome (AIDS).
Attempts have been made to reduce the dangers of contaminated syringe needles. Most commonly, the needle is simply covered with a plastic cap which fits over the needle and can be removed for use and replaced after use. This solution is often unsatisfactory since the nurse or doctor must manually place the cap back over the end of the needle. Many accidental pricks and contact with contaminated needles have occurred while attempting to replace the cap over the contaminated needle.
Other attempts to solve these problems are illustrated by U.S. Pat. Nos. 4,356,822; 4,573,976 and 4,631,057. These patents, in general, show specially made syringes having external telescoping sleeves mounted about the syringe barrel and adapted to be telescoped outwardly to surround the needle and telescope inwardly to expose the needle. While these devices, in general, can reduce the risk of accidental contact with a contaminated needle, they require that the entire syringe be specially formed and manufactured with complex sliding and locking mechanisms which not only tend to interfere with the use of the syringe, but can also be prohibitively expensive to manufacture relative to the common syringe. Further, these devices are not usable with a standard syringe to address the problems related to accidental contact.
A continuing need exists, therefore, for a simple to operate, efficient and inexpensive method of preventing accidental contact with contaminated syringe needles that can also be used with standard syringes. It is to the provision of such a method and apparatus that the present invention is primarily directed.